Exploring the Underworld: The geomorphology and sediments of subduction trenches
by Dr Heather Stewart, BGS Edinburgh
Thursday 16th September 2021 | 4.00pm - 5.00pm
Perspective view of the Kermadec Trench
Abstract
Subduction related trenches commonly display complex geomorphologies as a result of normal faulting, mass flow deposits, volcanism, accretion, canyons, inherent spreading fabric and formation of sedimentary basins. Not only controlling seafloor substrate heterogeneity, these features also form complex habitats for benthic fauna. Additionally, the funnelling of organic sediments, controlled by local topography and trench shape, to the trench axis is reported to influence biomass distribution in these dynamic environments. Over the last 5 years, the author has participated on four projects studying 17 trenches within the Pacific, Atlantic, Southern, and Indian oceans, providing a unique insight into global trench processes.
About the speaker
Heather Stewart is a marine geologist at the British Geological Survey, Edinburgh, UK. Her research concentrates on the geomorphology and geology of the sea floor and sub-sea floor from the coast to the hadal zone (depths exceeding 6000 metres). She looks at the processes including glaciation, faulting and modern-day sediment transport. She links her work on geomorphology, or shape of the sea floor, to the composition of the sea bed and how that varies over a wider geographic area, working with marine biologists to look at the impact of these on the biological communities that live there. Heather has participated on over 25 offshore expeditions around the world, has published on many aspects of marine geology and habitat research. Recently she was Expedition Geologist for the Five Deeps Expedition, the TV documentary of which will be broadcast on the Discovery Channel.